Magnesium based alloy

ABSTRACT

A magnesium based alloy consisting of, by weight: 2-5% rare earth elements, wherein the alloy contains lanthanum and cerium as rare earth elements and the lanthanum content is greater than the cerium content; 0.2-0.8% zinc; 0-0.15% aluminium; 0-0.5% yttrium or gadolinium; 0-0.2% zirconium, 0-0.3% manganese; 0-0.1% calcium; 0-25 ppm beryllium; and the remainder being magnesium except for incidental impurities.

FIELD OF THE INVENTION

The present invention relates to magnesium based alloys and, moreparticularly, to magnesium based alloys which can be cast by highpressure die casting (HPDC).

BACKGROUND TO THE INVENTION

With the increasing need to limit fuel consumption and reduce harmfulemissions into the atmosphere, automobile manufacturers are seeking todevelop more fuel efficient vehicles. Reducing the overall weight ofvehicles is a key to achieving this goal. Major contributors to theweight of any vehicle are the engine and other components of thepowertrain. The most significant component of the engine is the cylinderblock, which makes up 20-25% of the total engine weight. In the pastsignificant weight savings were made by introducing aluminium alloycylinder blocks to replace traditional grey iron blocks, and furtherweight reductions of the order of 40% could be achieved if a magnesiumalloy that could withstand the temperatures and stresses generatedduring engine operation was used. Development of such an alloy, whichcombines the desired elevated temperature mechanical properties with acost effective production process, is necessary before viable magnesiumengine block manufacturing can be considered.

HPDC is a highly productive process for mass production of light alloycomponents. While the casting integrity of sand casting and lowpressure/gravity permanent mould castings is generally higher than HPDC,HPDC is a less expensive technology for higher volume mass production.HPDC is gaining popularity among automobile manufacturers in NorthAmerica and is the predominant process used for casting aluminium alloyengine blocks in Europe and Asia. In recent years, the search for anelevated temperature magnesium alloy has focused primarily on the HPDCprocessing route and several alloys have been developed. HPDC isconsidered to be a good option for achieving high productivity rates andthus reducing the cost of manufacture.

WO2006/105594 relates to a magnesium based alloy consisting of, byweight:

1.5-4.0% rare earth element(s),

0.3-0.8% zinc,

0.02-0.1% aluminium,

4-25 ppm beryllium,

0-0.2% zirconium,

0-0.3% manganese,

0-0.5% yttrium,

0-0.1% calcium, and

the remainder being magnesium except for incidental impurities.

Alloys according to WO2006/105594 have demonstrated excellent hightemperature creep properties but have proven somewhat difficult to diecast. The present inventors have ascertained that fluidity and hottearing resistance during die casting and the oxidation resistance ofthe molten alloy is improved by increasing the proportion of lanthanumin alloys according to WO2006/105594.

Throughout this specification the expression “rare earth” is to beunderstood to mean any element or combination of elements with atomicnumbers 57 to 71, ie. lanthanum (La) to lutetium (Lu).

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a magnesium basedalloy consisting of, by weight:

2-5% rare earth elements, wherein the alloy contains lanthanum andcerium as rare earth elements and the lanthanum content is greater thanthe cerium content;

0.2-0.8% zinc;

0.02-0.15% aluminium;

0-0.5% yttrium or gadolinium;

0-0.2% zirconium;

0-0.3% manganese;

0-0.1% calcium;

0-25 ppm beryllium; and

the remainder being magnesium except for incidental impurities.

The total lanthanum and cerium content of the alloy is preferably1.5-3.5% by weight, more preferably 1.8-3.0%, and most preferably2.0-2.8%. Without wishing to be bound by theory, the lanthanum andcerium improve the castability and also the creep strength of the alloy.Again, without wishing to be bound by theory, a greater lanthanumcontent than cerium content further improves the castability of thealloy, particularly the hot tearing resistance of the alloy. Higherratios of lanthanum to cerium typically give the alloy greater ductilityand even greater resistance to hot tearing. Typically, a higher totallanthanum and cerium content is beneficial to the creep resistance ofthe alloy with a concomitant reduction in the ductility of the alloy.

The rare earth element content of the alloy may optionally containneodymium, in which embodiment the rare earth element content ispredominantly lanthanum, cerium and neodymium. Without wishing to bebound by theory, the inclusion of neodymium improves the creepresistance of the alloy. However, the neodymium content of the alloy maybe reduced to improve the castability of the alloy, in particular itsresistance to hot tearing. When present, the neodymium content ispreferably 0.5-2.0% by weight of the alloy, more preferably 0.5-1.5% byweight, more preferably about 1% by weight.

Various of the rare earth elements are typically derived from alanthanum misch metal containing lanthanum, cerium, optionallyneodymium, a modest amount of praseodymium (Pr) and trace amounts ofother rare earths. In another embodiment, the rare earth elements can bederived from a cerium misch metal, together with pure lanthanum toprovide the greater lanthanum content relative to the cerium content.For alloys that require a low cerium content, the rare earth elementsmay be derived from a commercial purity source of lanthanum.

The neodymium may be derived from one or both of the above misch metals,a pure source of neodymium, didymium (a neodymium richneodymium-praseodymium alloy) or any combination thereof.

Yttrium is an optional component which may be included. Without wishingto be bound by theory, the inclusion of yttrium is believed to bebeneficial for both melt protection and creep resistance. However, theyttrium content of the alloy may be reduced to improve the castabilityof the alloy, in particular its resistance to hot tearing. When present,the yttrium content is preferably 0.005%-0.5% by weight, more preferably0.01-0.4% by weight, more preferably 0.05-0.3% by weight, and mostpreferably 0.1-0.2% by weight.

The lanthanum or cerium misch metal from which the rare earth elementsare derived may optionally also contain yttrium. The yttrium content maythus be derived from these misch metals. The yttrium content may also bederived from a pure source of yttrium, a magnesium-yttrium master alloyor any combination thereof with or without the misch metals.

Gadolinium is an optional element which may be included. Without wishingto be bound by theory, the inclusion of gadolinium is believed to bebeneficial to both creep resistance and the oxidation resistance of themelt. The gadolinium addition may be made instead of an yttriumaddition. The gadolinium addition may however be made in combinationwith an yttrium addition. When present, the gadolinium content ispreferably 0.005%-0.5% by weight, more preferably 0.01-0.4% by weight,more preferably 0.05-0.3% by weight, and most preferably 0.1-0.2% byweight.

Preferably, alloys according to the present invention contain at least94.0% magnesium, more preferably 95-96% magnesium, and most preferablyabout 95.3-95.7% magnesium.

The zinc content is 0.2-0.8% by weight, preferably 0.2-0.6%, morepreferably about 0.4%.

The aluminium content is preferably 0.05-0.15% by weight, morepreferably 0.08-0.12% by weight, more preferably about 0.1% by weight.Without wishing to be bound by theory, the inclusion of these smallamounts of aluminium in the alloys of the present invention is believedto improve the creep properties of the alloys.

The beryllium content is 0-25 ppm. When present, the beryllium contentis preferably 4-20 ppm, more preferably 4-15 ppm, more preferably 6-13ppm, such as 8-12 ppm although beryllium is preferably absent whenyttrium is present as yttrium has a similar effect to beryllium at lowyttrium levels. When present, beryllium would typically be introduced byway of an aluminium-beryllium master alloy, such as an Al-5% Be alloy.Without wishing to be bound by theory, the inclusion of beryllium isbelieved to improve the die castability of the alloy. Again, withoutwishing to be bound by theory, the inclusion of beryllium is alsobelieved to improve the oxidation resistance of the molten alloy and inparticular improves the retention of the rare earth element(s) in thealloys against oxidation losses.

Reduction in iron content can be achieved by addition of zirconium whichprecipitates iron from the molten alloy. Accordingly, the zirconiumcontents specified herein are residual zirconium contents. However, itis to be noted that zirconium may be incorporated at two differentstages. Firstly, on manufacture of the alloy and secondly, followingremelting of the alloy prior to casting. Preferably, the zirconiumcontent will be the minimum amount required to achieve satisfactory ironremoval. Typically, the zirconium content will be less than 0.1%.

Manganese is an optional component of the alloy. When present, themanganese content will typically be about 0.1%.

Calcium (Ca) is an optional component which may be included, especiallyin circumstances where adequate melt protection through cover gasatmosphere control is not possible. This is particularly the case whenthe casting process does not involve a closed system.

Ideally, the incidental impurity content is zero but it is to beappreciated that this is essentially impossible. Accordingly, it ispreferred that the incidental impurity content is less than 0.15%, morepreferably less than 0.1%, more preferably less than 0.01%, and stillmore preferably less than 0.001%.

In a second aspect, the present invention provides an engine block foran internal combustion engine produced by high pressure die casting analloy according to the first aspect of the present invention.

In a third aspect, the present invention provides a component of anautomotive powertrain formed from an alloy according to the first aspectof the present invention.

The component of the powertrain may be the engine block or a portion ofan engine such as a cover, sump or brackets.

The component of the powertrain may be the transmission housing oranother transmission component.

Specific reference is made above to powertrains but it is to be notedthat alloys of the present invention may find use in other elevatedtemperature applications as well as in low temperature applications.Specific reference is also made above to HPDC but it is to be noted thatalloys of the present invention may be cast by techniques other thanHPDC including thixomoulding, thixocasting, permanent mould casting andsand casting.

In a fourth aspect, the present invention provides an article formedfrom an alloy according to the first aspect of the present invention.

EXAMPLES Example 1

A high-Nd variant die casting alloy has a composition:

1.8 wt. % Nd

0.7 wt. % Ce

0.4 wt. % La

0.6 wt. % Zn

balance Mg

This alloy was removed from a proprietary cover gas protection known asAM-cover by immersing a cylinder with a 10 mm diameter hole in thebottom. Dry air at 2 l/min was introduced to the top of the cylinder.The base of the cylinder was immersed into the molten alloy to a depthof 50 mm and the condition of the surface of the melt was observed.

For this high-Nd alloy, the new molten surface turned black almostinstantly and blooms of flaming magnesium occurred shortly afterwards.

The addition of 53 ppm of yttrium via a 43% yttrium-57% magnesium masteralloy to the melt dramatically changed the oxidation behaviour of themelt. When the cylinder was inserted into the melt, the melt surfacestayed bright and shiny for 50 seconds before spot burning wasinitiated. For an addition of 250 ppm yttrium, the resistance to theonset of burning was also excellent.

A similar effect is also experienced with the addition of gadolinium tothe melt instead of yttrium. A gadolinium addition of 310 ppm wassufficient to delay the onset of spot burning in the cylinder test for60 seconds but is not as efficient as yttrium for this purpose.

Higher lanthanum variants of the alloy have been observed to behave in adifferent manner to the high-Nd variants. Test work was conducted on theoxidation behaviour of a high-La variant of the alloy containing:

1.6 wt. % La

0.9 wt. % Nd

1.1 wt. % Ce

0.6 wt. % Zn

balance Mg

The aforementioned cylinder test was again used. In removing the meltfrom the protective atmosphere and into dry air, the alloy remainedbright and shiny with no sign of oxidation or burning after 40 seconds.This alloy had a similar melt protection behaviour to the high-Ndvariant of the alloy with the addition of 50-100 ppm of yttrium. Yttriumaddition to this high-La version of the alloy is not required for meltprotection purposes.

Example 2

Ten alloys were prepared and chemical analyses of the alloys are set outin Table 1 below. The rare earths were added as a cerium-based mischmetal (which contained cerium, lanthanum and some neodymium) andelemental lanthanum and neodymium. The yttrium and zinc were added intheir elemental forms. The beryllium was added as an aluminium-berylliummaster alloy. The aluminium was added as this master alloy supplementedwith elemental aluminium or where beryllium was not added, as elementalaluminium alone. The zirconium was added through a proprietary Mg—Zrmaster alloy known as AM-cast. The balance of the alloys was magnesiumexcept for incidental impurities. Standard melt handling procedures wereused throughout preparation of the alloys.

TABLE 1 Alloys Prepared wt. % wt. % wt. % wt. % wt. % ppm wt. % ppm wt.% Zr Alloy Nd Ce La Y Zn Be Al Fe (total) A 1.47 0.49 1.71 <0.005 0.59<1 0.008 7 0.097 B 1.50 0.50 1.73 0.052 0.61 <1 0.008 8 0.080 C 1.350.47 1.70 0.037 0.60 <1 0.030 6 0.052 D 1.34 0.46 1.73 0.033 0.61 <10.055 5 0.040 E 1.33 0.46 1.73 0.027 0.61 <1 0.10 3 0.018 F 1.38 0.471.73 0.016 0.61 <1 0.59 7 0.018 G 0.88 1.13 1.87 <0.01 0.41 4 0.07 13 NAH 0.84 1.13 1.84 0.23 0.46 12 0.05 19 NA I 1.62 0.66 0.37 <0.005 0.50 20.02 12 NA J 1.69 0.28 0.68 <0.005 0.43 3 0.05 22 NA (NA: not analysed)

FIG. 1 shows the creep results for 177° C. and 90 MPa for Alloys A, B,C, D, E and F. This set of creep curves illustrates the dramatic effectthat compositional variations had on creep performance in alloys of thepresent invention. The control alloy (Alloy A) displayed a relativelypoor creep resistance under the imposed test conditions, entering intotertiary creep quite early in the test (<50 hours) and ending with 1.3%creep strain when the test was terminated at 600 hours. This wasconsistent with previous results for other alloy variants that containedno Al/Be addition for melt protection.

With the addition of yttrium (˜0.05 wt. %) the creep response improvedsubstantially (Alloy B). Although both Alloy A and Alloy B reached 0.1%creep strain at approximately the same time, 62 hours and 60 hoursrespectively, the onset of tertiary creep was delayed until much laterin the test for Alloy B.

The addition of a small amount of aluminium (˜0.03 wt. %) produced asignificant improvement in the creep response (Alloy C). This alloy didnot reach 0.1% creep strain under the imposed test conditions until ˜500hours and did not appear to have gone into tertiary creep up to the timeof the termination of the test (600 h). With an additional amount ofaluminium (−0.06 wt. %) a further improvement in the creep propertieswas observed (Alloy D), which did not reach 0.1% creep strain at allduring the duration of the test (0.04% creep strain after 600 hours).With a further increase in the aluminium content (Alloy E, ˜0.1 wt. %)the creep resistance began to decline (0.16 creep strain in ˜190 hours),although this was still considered to be relatively good. Finally, witha significant increase in the aluminium content (Alloy F, ˜0.6 wt. %)the creep response of the alloy deteriorated totally. Alloy F wasconsidered to have very poor creep resistance under the imposed testconditions. These results confirm that aluminium is an importantmicro-alloying addition in obtaining excellent creep properties.

FIG. 2 shows the creep results for 177° C. and 90 MPa for Alloys G andH. Both Alloys G and H had delayed tertiary creep to beyond the durationof the test. The creep resistance of Alloy H, as shown in FIG. 2,compared favourably to Alloy X prepared in accordance with WO2006/105594and having a composition by weight of:

0.68% zinc, 1.89% neodymium, 0.56% cerium, 0.33% lanthanum, <0.005% yttrium, 0.05% aluminium, <5 ppm iron 12 ppm beryllium

with the balance magnesium except for incidental impurities.

Tensile properties were measured in accordance with ASTM E8 at 20 and177° C. in air using an Instron Universal Testing Machine. Samples wereheld at temperature for 10 minutes prior to testing. The test specimenshad a circular cross section (5.6 mm diameter), with a gauge length of25 mm.

Tensile test results for various samples of the alloys are set out inTable 2.

TABLE 2 Tensile Test Data 20° C. 177° C. 0.2% Proof, 0.2% Proof, AlloyMPa UTS, MPa % Elong. MPa UTS, MPa % Elong. A 166.8 ± 1.6 175.6 ± 0.61.3 ± 0.5 129.1 ± 6.2  158.7 ± 11.8 6.6 ± 2.8 B 165.2 ± 3.1 171.7 ± 4.81.4 ± 0.5 125.5 ± 4.1 153.4 ± 8.1 5.3 ± 1.5 C 160.4 ± 5.8 171.7 ± 7.71.5 ± 0.5 124.2 ± 2.1 150.0 ± 0.6 5.4 ± 0.7 D 158.5 ± 4.5 175.4 ± 2.91.8 ± 0.6 123.4 ± 3.2 143.0 ± 5.2 3.9 ± 0.5 E 150.8 ± 1.9 170.0 ± 5.51.5 ± 0.6 121.3 ± 3.6 145.2 ± 5.8 4.8 ± 1.8 F 140.0 ± 1.4 173.4 ± 4.71.7 ± 0.6 106.1 ± 1.5 130.9 ± 3.4 3.7 ± 0.9 G 175.5 ± 2.6 183.7 ± 4.12.4 ± 0.9 118.7 ± 1.3 151.8 ± 2.6 6.7 ± 0.8 H 176.2 ± 1.6 179.3 ± 1.82.0 ± 0.3 132.4 ± 1.8 167.6 ± 3.8 7.5 ± 1.1

It is noted that Alloy G and Alloy H in particular both had very goodcastability. The processing window for which sound castings can beobtained is much wider for these two alloys than for Alloy X referred toabove. For good casting quality an alloy requires a low susceptibilityto hot tearing, good die filling characteristics and reducedsusceptibility to the formation of defects at the intersection of flowfronts in the die.

A castability test die was developed to assess the castability of a widerange of alloys in high pressure die casting (HPDC). Castings from thedie are shown in FIG. 3. The die was designed to have a complex shapesuch that it would be extremely difficult to produce good quality highpressure die castings using this die. FIG. 3( a) shows the channels of athree-part gating system on the right hand side of the casting (known inthe art as “runners”) through which the molten alloy flows into the die.The “overflows” can be seen on the opposing side (the left hand side) ofthe casting to the runners. The overflows and runners are broken offafter casting.

The castability test die was used to produce a casting of Alloy H. Theas-cast surface quality of this casting of Alloy H is shown in FIG. 3(b).

Example 3

Alloys I, J and H (see Table 1, Example 2) were cast by high pressuredie casting using the castability test die referred to above in Example2 to study the effect of lanthanum and cerium on the castability of thealloy.

FIG. 4 shows the internal defect structure of the same section of thecastings of (a) Alloy I, (b) Alloy J and (c) Alloy H. Alloy I (0.66% wtcerium, 0.37% wt lanthanum) was found to have a large amount of internalcracking after casting. By changing the lanthanum to cerium ratio togreater than 1:1 in Alloy J (0.68% wt lanthanum, 0.28% wt cerium) theamount of internal cracking can be seen in FIG. 4( b) to have beenreduced and the overall quality of the casting improved. Furtherimprovement in the castability was found for Alloy H which has a greatertotal lanthanum and cerium content (1.7% wt lanthanum, 1.1% wt cerium)as well as a ratio of lanthanum to cerium above 1:1 and a reducedneodymium content (0.7% wt neodymium compared to 1.62% wt neodymium inAlloy 1 and 1.69% wt in Alloy J). Almost no internal cracking wasobserved for the casting of Alloy H. It can also be seen in FIG. 4( c)that Alloy H has a good resistance to the formation of internal flowdefects and hot tearing.

Without wishing to be bound by theory, the probable reason for thissecond observation can be explained with reference to FIG. 5 which showsthe temperature versus fraction solid curves for Alloys I and H based onGulliver-Scheil model calculations using the phase diagrams of magnesiumwith each of the individual rare earth elements assuming complete mixingwithin the alloy. Alloy H, which has a higher lanthanum content thanAlloy I can be seen to have a shorter freezing range. This is known toreduce the susceptibility of the alloy to hot tearing. Alloy H also hasan increased amount of eutectic over Alloy I. This is evidenced by thelast part of solidification of the Alloys which is occurring at the sametemperature. For Alloy H this occurs for a greater fraction of the alloyand thus for a longer period of time as compared to Alloy I. Thisfurther reduces the susceptibility of Alloy H to hot tearing. It isnoted that lanthanum is more efficient than cerium in changing thesolidification characteristics to reduce the alloy's susceptibility tohot tearing. This is because for alloys with the same total cerium pluslanthanum contents, the eutectic proportion is greater in solidifyinglanthanum-rich alloys and the eutectic temperature is also higher.

Again, without wishing to be bound by theory, a reduction in flow lineswhen high pressure die casting using Alloy H as compared to Alloy I isalso likely to be responsible for the reduction in internal cracking inAlloy H. Flow lines are formed during HPDC where flows of molten alloyfrom runners into the die meet the flow of other runners. Oxidation ofthe alloy occurs on the surfaces of these flows which meet to form thevisible flow lines of oxidised alloy within the casting. Without wishingto be bound by theory, it is believed that the higher yttrium content inAlloy H is responsible for this effect as this improves the recoveryrate of beryllium from the master alloy addition and also influences theberyllium's oxidation rate from the molten alloy.

FIG. 6 illustrates the improved surface appearance of HPDC castings from(a) Alloy I and (b) Alloy H, with the higher lanthanum and berylliumcontent alloy (Alloy H) having a much improved surface appearance.

Example 4

Five further alloys were prepared to study the effects of the neodymiumaddition. The alloys were prepared in accordance with the proceduresdescribe above in Example 2. Table 3 below provide the chemical analysisof these further alloys (K—P).

TABLE 3 Alloys Prepared wt. % wt. % wt. % wt. % wt. % ppm wt. % ppm wt.% Zr Alloy Nd Ce La Y Zn Be Al Fe (total) K 0.01 0.52 1.49 0.05 0.41 <10.05 73 0.0 L 0.22 0.84 1.80 0.01 0.41 <1 0.023 108 0.0 M 0.45 0.53 1.520.03 0.41 <1 0.05 86 0.0 N 0.73 0.46 1.42 0.02 0.42 <1 0.04 107 0.0 P0.93 0.39 1.42 0.04 0.42 <1 0.032 121 0.0

FIG. 7 shows the creep results for Alloy K to Alloy P at 177° C. and 90MPa. It can be seen from FIG. 7 that the creep response improves with anincrease in the neodymium content of the alloy (refer to Table 3). AlloyK, Alloy M, Alloy N and Alloy P also have very similar compositions inall the other alloying elements except for the neodymium content. Thecurves indicate that the neodymium content in the alloy should begreater than about 0.5 wt.% in order to obtain a creep response that issuitable for elevated temperature applications.

1. A magnesium based alloy consisting of, by weight: 2-5% rare earthelements, wherein the alloy contains lanthanum and cerium as rare earthelements and the lanthanum content is greater than the cerium content;0.2-0.8% zinc; 0-0.15% aluminium; 0-0.5% yttrium or gadolinium; 0-0.2%zirconium; 0-0.3% manganese; 0-0.1% calcium; 0-25 ppm beryllium; and theremainder being magnesium except for incidental impurities.
 2. Amagnesium based alloy as claimed in claim 1 wherein the ratio oflanthanum to cerium in the alloy is greater than 1:1.
 3. A magnesiumbased alloy as claimed in claim 1 wherein the alloy also containsneodymium as a rare earth element, and the lanthanum content of thealloy is greater than the neodymium content.
 4. (canceled)
 5. Amagnesium based alloy as claimed in claim 3 wherein the cerium contentof the alloy is greater than the neodymium content.
 6. (canceled)
 7. Amagnesium based alloy as claimed in claim 3 wherein the neodymiumcontent of the alloy is, by weight 0.5-2.0%.
 8. A magnesium based alloyas claimed in claim 3 wherein the neodymium content of the alloy is, byweight 0.5-1.5%.
 9. A magnesium based alloy as claimed in claim 1,wherein the total lanthanum and cerium content of the alloy is, byweight 1.5-3.5%.
 10. A magnesium based alloy as claimed in claim 1,wherein the total lanthanum and cerium content of the alloy is, byweight 1.8-3.0%.
 11. A magnesium based alloy as claimed in claim 1,wherein the total lanthanum and cerium content of the alloy is, byweight 2.0-2.8%.
 12. A magnesium based alloy as claimed in claim 1,wherein the yttrium content is by weight 0.005-0.5%.
 13. A magnesiumbased alloy as claimed in claim 1, wherein the gadolinium content is byweight 0.005-0.5%.
 14. A magnesium based alloy as claimed in claim 1,wherein the alloy consists of by weight at least 94% magnesium.
 15. Amagnesium based alloy as claimed in claim 1 wherein the zinc content isby weight 0.2-0.6%.
 16. A magnesium based alloy as claimed in claim 1wherein the aluminium content is by weight 0.05-0.15%.
 17. A magnesiumbased alloy as claimed in claim 1 wherein the zirconium content is lessthan 0.1% by weight.
 18. A magnesium based alloy as claimed in claim 1,wherein the beryllium content is by weight 8-12 ppm.
 19. A magnesiumbased alloy as claimed in claim 1, wherein the manganese content is byweight approximately 0.1%.
 20. (canceled)
 21. An engine block for aninternal combustion engine produced by high pressure die casting analloy as claimed in claim
 1. 22. A component of a powertrain formed froman alloy as claimed in claim
 1. 23. An article formed from an alloy asclaimed in claim 1.